The present invention relates generally to devices for converting wind forces to usable energy, and more particularly to an overspeed and power control system for vertical axis wind turbines.
U.S. Pat. No. 1,825,500 to Banker, U.S. Pat. No. 1,846,162 to Thomas, U.S. Pat. No. 4,236,504 to Cornelison Jr., and U.S. Pat. No. 4,293,274 to Gilman disclose vertical axis wind turbines which have means for spoiling the aerodynamics of the rotating vanes when the rotation is too fast, such as the result of high winds. The spoiling of the aerodynamics is brought about by centrifugal force acting directly on the vanes or by suitable linkage means that are responsible to the centrifugal forces of high speed rotation.
The devices disclosed in these various patents do, however, have certain drawbacks. The spoiler means of the various devices are structurally complex and expensive to assemble. Also, maintenance of the spoiler means is often made difficult due to the remote physical location of the devices. The structural integrity of the turbine blades is often compromised where the spoiler is attached to the blade. Finally, the drag of these devices in their undeployed position has a degrading effect on the aerodynamic performance of the vertical axis wind turbine.